Adjustable backrest

ABSTRACT

An adjustable backrest for supporting a human back comprising a straight spine member; a lumbar support member projecting from the straight spine member; an upper back support member projecting from the straight spine member adjacent the lumbar support member; a back pad resting on the lumbar support member and the upper back support member for supporting the human back; means for adjusting curvature of the lumber support member and means for adjusting curvature of the upper back support member to accommodate different shapes of the human back; means for providing side-to-side mobility of the back pad to accommodate twisting movement of the human back.

FIELD OF THE INVENTION

The present invention relates in general to backrests, and moreparticularly an adjustable backrest having independent adjustment oflumbar and upper back height and curvature, as well as overall heightadjustment to fit different size patients.

BACKGROUND OF THE INVENTION

Adjustable backrests or supports are well known in the art. U.S. Pat.No. 5,112,106 (Asbjornsen et al) discloses a backrest comprising acentral spine or rail to which a lumbar support cushion and head cushionare connected via a sliding element. The sliding element is connected tothe rail or spine via a ratchet-like connection. The '106 Patent is ofinterest for teaching the concept of height adjustable lumbar supportwhere the adjusting means is connected to a spine for sliding engagementtherewith.

U.S. Pat. No. 2,756,809 (Endresen) discloses a back support comprising ametal sheet with adjustable lumbar and upper-back portions. A screwadjusts the concavity of the upper-back portion while a further screwadjusts the convexity of the lumbar support portion. A pair of crossbars are provided for supporting and securing the lumbar and upper backportions of the sheet to the backrest. The two adjustment screws aremounted on a pair of sliding plates to provide vertical adjustment ofthe lumbar support area and the upper-back support area. Accordingly,this patent is of interest for teaching independent height and curvatureadjustment of the lumbar support and upper-back support portions of abackrest.

Additional references are known which pertain to adjustable back supportor backrests, as follows: U.S. Pat. Nos. 2,843,195; 3,241,879;3,762,769; 4,153,293; 4,452,458; 4,541,670; 4,601,514; 4,632,454;4,722,569; 4,909,568; 4,915,448; 4,968,093; 5,026,116; and 5,197,780, aswell international patent application No. PCT/AU91/00487 (BackCare andSeating Pty. Ltd.).

While the known prior art backrests disclose the provision of lumbar andupper-back support members with independently adjustable curvature andpositioning, none of the known prior art teaches the combinations ofheight adjustment, lumbar height and curvature adjustment, upper-backcurvature and position adjustment and side-to-side mobility. Theprovision of these features in a backrest is important to ensure properfitting of the backrest for adult bodies of different height and shapes.Furthermore, human beings tend not to be static but like to move or"fine tune" their sitting positions. The known prior art backrests donot provide adequate side-to-side mobility for such movement. Nor dothey allow for the convenient minor adjustment of support. In addition,the known prior art back supports are generally bulky or heavy to carryand occupy excessive space at the bottom portions thereof, therebyleaving very little room to sit on a chair.

SUMMARY OF THE INVENTION

According to the present invention, a backrest is provided in whichlumbar height and curvature adjustment are provided along with overallheight adjustment to fit different sized persons. Additionally,upper-back curvature and height adjustment are provided along with sideadjustment to suit each half side of the human back (i.e. foraccommodating different torso shapes). Also, side-to-side mobility isprovided to accommodate twisting movements of the human back which arecommon when a person is sitting (e.g. turning to reach something, or"fine tuning" of one's sitting position). Furthermore, according to thebackrest of the present invention a slight hollow is provided just abovethe base of the backrest to allow for curvature and space so that thebackrest does not occupy excessive space on a chair.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the backrest according to the presentinvention resting on a chair;

FIG. 2 is a cross section along lines II--II of FIG. 1;

FIG. 3 is a rear perspective view of the backrest according to thepresent invention;

FIGS. 4A and 4B are cross sectional views along the lines IV--IV of FIG.3 showing curvature adjustment of the lumbar support and upper backsupport of the backrest according to the present invention;

FIG. 5 is a front perspective view of the backrest according to thepresent invention with back pads shown in phantom; and

FIG. 6 is an exploded front perspective view of the structural detailsof the backrest according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning first to FIG. 1, the backrest of the present invention is showncomprising a generally triangular upper portion 1 and base portion 3resting on the seat of chair C. The triangular profile of upper portion1 facilitates side-to-side movement of a person using the backrest ofthe present invention. Also, the hollow portion between the portion 1and base portion 3 ensures that the backrest does not occupy excessivespace on the chair C.

Turning to the remaining FIGS. 2-6, the details of construction of thepreferred embodiment are illustrated. A spine 5, preferably of rigidaluminum, forms a central support portion of the backrest to which allother parts are attached. The spine 5 is fabricated to form a pair ofcylindrical channels 7 and 9 intermediate a groove 11. As will bediscussed in greater detail below, the spine 5 also includes a pluralityof slots and apertures for the connection and securing of the variousother parts.

A lumbar spring 13 has a projection 15 from a bottom end thereof whichis shaped so as to be received in a clip 17. The clip 17 is riveted intospine 5 via a rivet 19 or other suitable attachment means. Thus, thelower portion of lumbar spring 13 is rigidly connected to the spine 5.As will be discussed in greater detail below, an upper portion of thelumbar spring 13 contains a projection 21 which is adapted to slidewithin the groove 11 of the spine 5 to permit curvature adjustment ofthe lumbar spring 13.

A cross bar 23 is provided in the form of a flat piece of metal (e.g.steel) which is resilient for contributing to side-to-side mobility ofthe backrest. The cross bar 23 is attached to back pad 4a as discussedin greater detail below.

An adjustment strap 25 is provided with a clip 27 at one looped endthereof and a D-ring 29 at an opposite looped end thereof. The end withclip 27 is dimensioned to pass through an aperture 31 in the spine of 5as shown by the arrow in FIG. 6 such that the clip 27 may be secured toone of a plurality of slots 33 in the spine.

At the other end, the projection 21 of lumbar spring 13 is dimensionedto pass through D-ring 29 which remains on an opposite side of the spine5 from the clip 27 and is adapted to slide within the groove 11 thereof,as will be discussed in greater detail below.

According to an important aspect of the present invention, curvature ofthe lumbar spring 13 may be adjusted. Turning to FIGS. 4A and 4B, themanner of such adjustment is shown. In order to adjust the curvature ofspring 13, the clip 27 at the lower looped end of adjustment strap 25 isremoved from one of the slots 33 in spine 5 by pulling downwardlyagainst the tension of the spring 13 and releasing. Pulling of theadjustment strap 25 is facilitated by the loop 39 through which a fingermay be inserted. Once the clip 27 has been removed from the slot 33, asshown in FIG. 4B, curvature of the lumbar spring 13 may be decreased byallowing the adjustment strap 25 to be released upwardly toward the slot31 in spine 5. Alternatively, as shown in FIG. 4B, by pulling downwardlyon the adjustment strap 25, D-ring 29 pulls the projection 21 of lumbarspring 13 downwardly, thereby increasing the curvature of the spring inthe direction of the arrow.

An upper back spring 35 is provided having a slot 37 at a base portionthereof through which the projection 21 is adapted to be inserted (shownbest in FIGS. 5 and 6).

According to another important aspect of the invention, independentcurvature of the upper back spring 35 is also provided. A cylindricaltube 41 is capped on both sides via end caps 43, and is secured to thespine 5 via retention spring 45 which slides within the groove 11 andwhich is riveted to the upper back support tube 41 via rivet 47. Bypushing the tube 41 downwardly in the direction of the arrow in FIG. 4B,the upper back spring 35 assumes a greater degree of curvature (i.e.concavity), as illustrated. In addition, the tube 41 may be easilyremoved in order to remove any curvature in the upper back spring 35.

A back pad 49 (FIG. 5) is provided with a pair of adjustment straps 51and 53 having hook and loop type fasteners thereon (i.e. velcro™) whichpass through a pair of slots 55 in the back pad 49 in order to adjustthe contour of back pad 49, as discussed in greater detail below. Eachof these straps is independently and individually adjustable of eachother allowing for precise side-to-side contouring.

The back pad 49 is connected to the upper spring 35 via a screw (notshown) or other attachment means passing through holes 57 and 59 (FIG.5). The back pad 49 is connected at a lower end thereof to a furtherretention spring 61 which slides within the groove 11. Back pad 49 isconnected to retention spring 61 via rivet 63 and hole 65 (FIG. 5).Thus, the back pad 49 is free to move upwardly and downwardly relativeto the spine 5 as a result of the sliding connection of retention spring61, upper back support spring 35 and cross bar 23 which is mounted tolumbar support spring 13.

As shown in FIGS. 1, 2 and 3, the back pad 49 is covered by a suitablefabric and foam cover 67 which provides a soft cushion for receiving thehuman back, the overall vertical profile of the cushion being dictatedby the curvatures of the lumbar support spring 13, upper back supportspring 35 and back pad curvature adjustment straps 51 and 53. As shownin FIG. 3, the back pad adjustment straps are attached via rivets orother suitable means to the back pad 49 via apertures 69, and extendthrough the rear of the fabric and foam cushion 67 via slots 71 and 73for connection rearwardly of the backrest to suitable hook-and-loop(i.e. Velcro™) fasteners 75 (see FIGS. 2 and 3). By pulling on theadjustment straps 51 and 53, the curvature of the back pad 49 and hencethe cushion 67 covering it, is caused to increase in the direction ofthe arrows shown in FIG. 3.

The base portion 3 of the backrest includes a wire foot 77 covered withself skinning plastic foam 79. As shown in FIG. 6, cylindrical endportions of the wire foot 77 are adapted to slide within the cylindricalholes 7 and 9 (FIG. 2) of the spine 5 for upward and downward slidingmovement of the wire foot 77 as shown with reference to the arrows atthe bottom of FIG. 3. The wire foot 77 is secured in place relative tospine 5, after height adjustment, by means of a pair of screws 80 andcorresponding nuts 82.

A self skinning wire head 81 is inserted into the tubular grooves 7 and9 at the top of spine 5 to provide a pleasing aesthetic finish and anintegral carrying handle. The wire head 81 is secured within spine 5 viaa pair of screws 83 and corresponding nuts 85 which cause the grooves 7and 9 to close around the wire head 81. In order to assemble thebackrest according to the present invention, cross bar 23 is firstattached to the lumbar spring 13 using very high bond tape, or othersuitable material, as discussed above. The Velcro™ adjustment straps 51and 53 and the cross bar 23 are then riveted to back pad 49. Lumbarspring 13 and upper back spring 35 are hooked together as shown in FIG.6, and the upper back spring 35 is riveted to the back pad 49 asdiscussed with reference to FIG. 5. The retention spring 61 is rivetedto the back pad 49 through hole 65 (FIG. 5).

Clip 27 is then riveted to the lumbar adjustment strap 25, forming aloop 39.

Wire foot 77 is inserted into the spine 5 and fastened into place withmachine screws 80 and nuts 82. Loop 29 is hooked to the lumbar spring 13and this assembly is then made to slide into the channel 11 in the spine5. The lumbar adjustment strap 25 is then inserted through the D-shapedloop and riveted to the end thereof, and the opposite looped end 39 ofthe strap 25 is pushed through slot 31 at the back of the spine 5. Theassembly comprising lumbar spring 13, D-shaped loop 29 and upper backspring 35 is pulled downwardly to allow the retention spring 61 to slideinto the spine 5 from the bottom. The assembly is then pulled back upand the bottom end 15 of the lumbar spring 13 is hooked into clip 17.

Next, the retention spring 45 is riveted to the upper back support tube41. End caps 43 are inserted into the sides of the upper back supporttube 41, and the assembly comprising the upper back support spring 35and retention spring 45 are inserted into the channel 11 of spine 5 fromthe top.

The wire head 81 is then inserted into the top of the spine 5, thefabric and foam cover 67 is placed over the back pad 49, and the variousstraps 25, 51 and 53 are adjusted for personal setting.

In summary, according to the present invention, an adjustable backrestis provided having independent lumbar height and depth adjustment,overall height adjustment to fit different sized patients, mid-backcurve height adjustment, side adjustment to suit each half of apatient's back, upper back side-to-side mobility so that the patient canturn from side-to-side, and a hollow portion just above the base toallow curvature and room so that the backrest of the present inventiondoes not occupy excessive space on the chair. Furthermore, the backrestaccording to the preferred embodiment is portable, and can be affixed tooffice chairs, car seats, wheelchairs, etc.

Other embodiments and modifications of the invention are contemplated.For example, in a further alternative embodiment the backrest of thepresent invention may be incorporated integrally within a chair, ratherthan being portable as provided in the preferred embodiment. Thisfurther alternative embodiment nonetheless offers all of the advantagesof independent adjustability provided by the preferred embodiment. Thisand all other modifications and embodiments are believed to be withinthe sphere and scope of the invention as defined by the claims appendedhereto.

We claim:
 1. An adjustable backrest for supporting a human backcomprising:a) a straight spine member; b) a lumbar support memberprojecting from said straight spine member; c) an upper back supportmember projecting from said straight spine member adjacent to saidlumbar support member; d) a back pad resting on said lumbar supportmember and said upper back support member for supporting said humanback, said back pad including a pair of individually adjustable sidesupport members; e) lumbar adjustment means connected to said lumbarsupport member for adjusting curvature of said lumbar support memberrelative to said straight spine member to accommodate different sizesand shapes of lower back portions of said human back; f) upper backadjustment means connected to said upper back support member foradjusting curvature of said upper back support member relative to saidstraight spine member to accommodate different sizes and shapes of upperback portions of said human back; g) said adjustment means connected tosaid side support members for independently adjusting curvature of eachof said pair of individually adjustable side support members relative tosaid back pad to accommodate different side contours of said human back;h) means connected to said straight spine member and said back pad forproviding side-to-side mobility of said back pad to accommodate twistingmovement of said human back.
 2. The adjustable backrest of claim 2,further comprising length adjustment means for adjusting the length ofsaid straight spine member to accommodate different lengths of saidhuman back.
 3. The adjustable backrest of claim 2, wherein said lengthadjustment means further comprises a wire foot connected to a baseportion of said straight spine member for adjustable sliding movementwith respect thereto.
 4. The adjustable backrest of claim 1, whereinsaid lumbar support member further comprises a generally convex springconnected to said straight spine member.
 5. The adjustable backrest ofclaim 4, wherein said generally convex spring is connected at one end tosaid straight spine member and secured at an opposite end for slidingmovement relative to said spine member.
 6. The adjustable backrest ofclaim 5, wherein said lumbar adjustment means further comprises anadjustment strap having a clip at one end for hooking into one of aplurality of vertically arranged slots in said spine member, and acarriage loop at an opposite end for connection to said opposite end ofsaid convex spring, whereby curvature is increased in response topulling downwardly on said adjustment strap and curvature is decreasedin response to releasing said adjustment strap upwardly.
 7. Theadjustable backrest of claim 1, wherein said upper back support memberfurther comprises a generally concave spring having a free endprojecting from said spine member and opposite end secured to saidstraight spine member for sliding movement relative thereto.
 8. Theadjustable backrest of claim 7, wherein said upperback adjustment meansfurther comprises a cylindrical tube connected to an upper portion ofsaid spine member intermediate said spine member and said free end ofsaid concave spring, and means for adjusting vertical position of saidcylindrical tube on said spine member to vary the curvature of saidconcave spring.
 9. The adjustable backrest of claim 8, wherein saidmeans for providing side-to-side mobility comprises a first retentionspring for connecting said cylindrical tube to said spine member and asecond retention spring for connecting said back pad to said spinemember, said first retention spring and said second retention springpermitting rocking movement of said cylindrical tube and cylindricaltube on said spine member to vary the curvature of said concave spring.10. The adjustable backrest of claim 1, further comprising a cross barconnected to a central portion of said lumbar support member, said crossbar having a pair of opposite wing portions extending perpendicular tosaid spine member.
 11. The adjustable backrest of claim 9, wherein saidback pad is connected to said cross bar and said upper back supportmember for movement therewith and also slidably connected to said spinemember.
 12. The adjustable backrest of claim 10, wherein said sideadjustment means further comprises a pair of adjustment straps eachconnected at one end to respective ones of said wing portions, said pairof adjustment straps passing through respective apertures in said backpad, and free ends of each of said adjustment straps being connectableto respective hook and loop type fasteners on an opposite side of saidback pad than said cross bar, whereby curvature of said back pad may beadjusted by adjusting the length of said pair of adjustment straps. 13.The adjustable backrest of claim 1, wherein said back pad is covered byresilient foam.